Carburetor system



June 14, 1955 R. L. M DONNELL 2,710,605

1 CARBURETOR SYSTEM Filed Jan. 21, 1953 y I I 2 Sheets-Sheet l INVENT OR RANMLL L. MC DONNELL BY WW1 ATTORNEYS June 1955 R. L. M DONNELL CARBURETOR SYSTEM 2 Sheets-Sheet 2 Filed Jan. 21, 1953 INVENT OR RANDALL L. Mc DONNELL ATTORNEYS 2,710,605 Patented June 14, 1955 Free a htates CARBURETOR SYSTEM Randall L. McDonnell, Hattiesburg, Miss.

' Application January 21, 1953, Serial No. 332,172

7 Claims. (Cl. 123133) This invention relates generally to an improvement in carburetor systems for use with conventional type carburetors installed in automotive, marine and stationary engines and has particular relation to a carburetor system involving the collection of unvaporized fuel in the carburetor, the vaporization of the collected fuel in a conduit heated by the engine exhaust gases and the discharge of the vaporized fuel into the engine intake manifold, the device being either in the form of a carburetor system per se or in the form of an attachment for conventional carburetors of the down-draft or up-draft type.

Conventional type carburetors discharge fuel from the main discharge nozzle at low pressure and under this low discharge pressure the fuel is imperfectly vaporized. Unvaporized or imperfectly vaporized fuel will not burn completely in the internal combustion engine and the unburned portion results in a waste of power and promotes ring sticking, carbon formation, oil dilution and engine wear.

Accordingly, it is an object of this invention to provide an improved carburetor system which promotes more complete vaporization of the fuel supplied to internal combustion engines of the type using gasoline or other liquid hydrocarbon fuels.

It is another object of this invention to provide a collector attachment for a carburetor which will collect a substantial amount of the fuel introduced into the carburetor from the nozzle and conduct the fuel to heating means disposed in the exhaust pipe, from whence it is conducted in a highly vaporized state to the intake manifold.

A further object is to provide a carburetor attachment which may be used with virtually all engines employing single or multiple barrel carburetors of the down-draft or up-draft type.

Still another object of this invention is to provide fuel collector means and vaporized means for a carburetor system which may be simply attached to conventional carburetors and may be durably yet economically constructed by virtue of the fact that close tolerances are not required.

It is still another object of this invention to provide an improved carburetor system or a carburetor attachment which operates dependably over the entire range of operating conditions obtaining in internal combustion engine operations.

Other objects of the present invention are similar to those set forth in my earlier issued U. S. Patent No. 2,582,389 which discloses and claims a carburetor system including fuel collecting means. The fuel collector comprising the present invention is more efiicient, however, than the collector described in the above mentioned patcut, for it collects a greater percentage of the fuel discharged from the main discharge nozzle over a wider range of operating conditions.

Some of the objects having been stated, others will be apparent to those skilled in the art when the specification is read in connection with the drawings in which:

Fig. 1 is an elevation with parts broken away, showing my improved collector and vaporizer attachment operably connected with a standard type carburetor;

Fig. 2 is an enlarged view with parts broken away, showing the manifold pressure-responsive valve and the connections for the same;

Fig. 3 is an enlarged view showing the connection for the nozzle extension;

Fig. 4 is an enlarged view showing the nozzle extension and the fuel collector element With parts broken away, and

Fig. 5 shows a modification of the device shown in Fig. 4, showing a hollow fine-mesh screen ball surrounding the open end of the nozzle extension.

Referring more specifically to the drawings, a conventional carburetor is designated at 10. The main fuel discharge nozzle 11 extending from the float chamber 12 has an extension 13, open at its lower end reaching for a substantial distance into a tubular collector element 14 which is open at the top, as at 15. It will be noted that the top of the tubular collector element 15 is positioned adjacent the throat of the conventional venturi 16.

A fuel line or pipe broadly designated at 17 communicating with the bottom of the tubular collector element 14- extends for a substantial distance into the exhaust pipe 20, and has an open end 21 through which the fuel is introduced into a tubular element 22.

The connection between the main discharge nozzle 11 and the nozzle extension 13 must be leakproor. The tubular heating conduit 22 surrounds the lower portion of the fuel line 17 and is closed at its lower end, as at 23. Heated exhaust gases surrounding the tube 22 thoroughly vaporize the fuel conducted thereto. It has been demonstrated by actual road tests that the heater tube 22 must extend for a substantial distance into the exhaust pipe to be fully effective. Additionally, the tube 22 must be made of thin metal having high heat conductivity, thereby to be rapidly heated since the Warmup period of engine operation is the most critical from the standpoint of engine wear.

To a great extent, the exhaust type heater is inherently self-regulating. Thus, as the quantity of fuel burned by the engine increases, the quantity of exhaust gas heat also increases. This means that as the quantity of fuel flowing into the exhaust heater increases, the heat available to vaporize this fuel also increases and, of course, as the quantity of fuel used by the engine decreases the quantity of exhaust heat also decreases. To put it differently, the quantity of exhaust heat available to vaporize fuel in the exhaust heater will vary more or less directly as the quantity of fuel flowing into the exhaust heater.

Referring to Fig. 1 of the drawings, an intake manifold is designated by the numeral 25, and an exhaust manifold by numeral 26. The tubular heating element 22 communicates with the intake manifold through the open top end thereof, as at 27. A conventional type hotspot is shown at 30 and will be referred to in more detail later.

During operation, the air rushing past the throat of the venturi creates a drop in ambient pressure at the upper edge of the collector element 14. Fuel mixed with some air from the air bleed (not shown), is forced out of the nozzle 11 by atmospheric pressure acting on the float chamber, travels down the nozzle extension and wets the inside surface of the collector element 14. Gravity and inertia, together with the rush of air flowing into the collector element 14, cause the fuel to travel downwardly through the pipe 17 and to be discharged through the open end 21 into the tubular heating element 22. The hot gases in the exhaust pipe 20 thorough- 1y vaporize the fuel and discharge the vaporized fuel into the intake manifold from the open end 27 of the heating element 22. Thence, it is conducted by the air stream into the intake manifold to the cylinders (not shown). At all speeds or power output above the idling range an amount of air suflicient to take care of the volume of fuel being discharged is flowing downwardly into the tube. Because of the small amount of air passing into the intake manifold 25 the collector has very little effect on the balance that obtains among the various systems of the carburetor.

It is often desirable to place a manifold pressureresponsive valve broadly indicated at into the system, between the collector element 14 and the heating ele ment 22. This valve 35 is illustrated in detail in Fig. 2 of the drawings. The pipe 36 on the left hand end of the valve 35 communicates with the intake manifold 25 and the chamber 37 of the intake manifold pressureresponsive valve 35. The valve 35 includes a longitudinally extending shaft 40 biased by the spring 41. A rise in pressure in the intake manifold will cause the diaphragm 42, which is rigidly connected to the shaft 4 to move the same to the right in Fig. 2. An adjustment knob 43 is provided to adjust the bias of the spring 40 and thus vary the sensitivity of the valve 35. The shaft 41 carries a valve plunger 45, adapted to be unseated from the valve seat 46 to permit fuel from the pipe 17 to flow therethrough and be conducted down the pipe 17 to the heater element 22.

When the power output of the engine is low, the pressure in the intake manifold is low, and the valve plunger will be seated and allow no fuel to flow through the pipe 17. Thus, when the engine is operating in the idling range, or slightly above, the carburetor will operate in a conventional manner. Under normal operation, when the pressure in the intake manifold is higher, then the valve 45 will open commensurately and thus maintain the balance that normally obtains in the valve systems of the carburetor.

When the manifold pressure rises to a certain point some of the fuel will be discharged from the upper edge of the collector 14 and at wide open throttle nearly all of the fuel will be so discharged. It must be borne in mind. however, that wide open throttle operation is not considered normal operation. in the case of an automobile the vaporizer will operate efiiciently from approximately 25 miles per hour in high gear to at least miles per hour or the equivalent; of course it is also satisfactory for use in buses, trucks, tractors, boats, stationary engines, etc.

When the manifold pressure rises to a predetermined value (as at full throttle) the flow of fuel to the exhaust heater can be completely stopped by the seating of a second valve plunger 47 in the valve seat 46.

While only the manifold pressure-responsive type valve has been described herein, it is to be understood that any pressure-responsive or speed-responsive means such as a control valve operated by linkage to the throttle arm or shaft also would be very satisfactory.

Fig. 5 shows a modification of the collector 14. The bottom portion of the collector element 14 is shown to be slightly enlarged as at 14a and a hollow fine-mesh screen ball 14b is seated over and surrounds the end of the nozzle extension tube 13. This has a tendency normally to prevent fuel from flowing out of the open top of the collector 14.

It is to be understood that a collector unit 14 must be used with each main discharge nozzle of the carburetor on which the attachment is to be used, the carburetor having only one nozzle being shown for purposes of illustration. It is also to be understood that with slight modification. this collector and vaporizing unit may be used equally well with the up-draft, as Well as the downdraft, carburetor.

When a vaporizing system as herein described is used til it is usually unnecessary and often undesirable as well to use a hot-spot. To begin with the exhaust type heater will begin to thoroughly vaporize the fuel long before the hot-spot has even warmed up; this is, of course, due to the fact that the wall of the exhaust heater tube contains very little metal to warm up initially. In many cases the hot spot can be completely separated from the intake manifold by a little machining and spacing. Since the hot spot will warm the incoming air in some degree even though the valve is in the cold position after the engine has reached operating temperature, it is often desirable to eliminate it; this will improve the volumetric efficiency of the engine. It should be noted that the exhaust type heater will heat only the fuel and that its effect on the intake air temperature is negligible.

Thus. it is apparent that I have provided an improved fuel collector and vaporizer for internal combustion engine carburetor systems which eliminates one of the chief causes of engine wear by providing for complete fuel vaporization at all times.

While the present invention has been illustrated and described in its preferred embodiments, other variations and modifications may be made by those skilled in the art, and it is intended that all such variations and modifications be covered which fall within the spirit and scope of the appended claims.

I claim:

1. A fuel vaporizer attachment for an internal combustion engine carburetor system, said internal combustion engine including an intake manifold and an exhaust pipe, comprising. in combination, an open-top collector disposed adjacent a low pressure area of the carburetor, a fuel nozzle extension communicating with the open-top of said collector for introducing fuel therein, a fuel line communicating with said collector adapted to extend a substantial distance into said engine exhaust pipe, valve means associated with said fuel line for controlling the quantity and mixture of fuel passing therethrough and a heating conduit surrounding said fuel line adapted to extend into said exhaust pipe and be heated by the exhaust gases therein, said heating conduit being open at one end and closed at the other end, said open end adapted to communicate with said intake manifold whereby fuel may be vaporized in said heating conduit and be conducted to the intake manifold.

2. A fuel vaporizer as set forth in claim 1 wherein said fuel nozzle extension extends a substantial distance into said collector.

3. A fuel vaporizer as set forth in claim 2 wherein said fuel nozzle extension projects into a hollow fine mesh screen ball contained within said collector.

4. A fuel vaporizer as set forth in claim 1 wherein said valve means includes a manifold pressure-responsive valve.

5. A fuel vaporizer as set forth in claim 1 wherein said valve means is adapted to close at predetermined high and low pressures.

6. A fuel vaporizer as set forth in claim 5 wherein said valve means includes a manifold pressure-responsive valve.

7. An exhaust heater for vaporizing fuel in an internal combustion engine carburetor system, said internal combustion engine including an intake manifold and an exhaust pipe, comprising in combination an open-top collector disposed adjacent a low pressure area of the carburetor, a fuel nozzle extension extending a substantial distance into said collector for introducing fuel therein, fuel conducting means communicating with the bottom of said collector adapted to extend a substantial distance into said engine exhaust pipe. a manifold pressure-responsive valve adapted to close at predetermined high and low pressures associated with said fuel line for controlling the quantity and mixture of fuel passing therethrough and a thin heat-conducting tubular heater element disposed in the exhaust pipe and surrounding said fuel conducting means for receiving the fuel and vaporizing the same, said heater element being closed at one end and communicating with the intake manifold at the other, whereby vaporized fuel may be conducted into the intake manifold.

References Cited in the file of this patent UNITED STATES PATENTS 1,479,547 Kambak Jan. 1, 1924 6 Brush Oct. 8, 1929 Morgan Jan. 13, 1953 FOREIGN PATENTS France Dec. 16, 1926 

